1. Field of the Invention
The present invention relates to an object motion tracing technique for tracing the three-dimensional motion of an object obtained in time series on the basis of the stereo image of the object concerned, and also to a recording media wherein an executing program for object motion tracing is recorded.
2. Brief Description of the Prior Art
Generally, for tracing the three-dimensional rigid body movement of a curve-faced object, time-series images consecutively obtained from a visual sensor as an image pick-up means are used. If the form of the traced object is known, the tracing point can be estimated in correspondence search by using a three-dimensional geometric model of the object concerned, thereby realizing highly-accurate tracing of the position and the posture of the curve-faced object, wherein tracing is comparatively unaffected by partial occlusion.
Prior arts known for tracing the three-dimensional rigid body motion of an object using an object model are as follows:                (1) Method of using a monocular CCD camera as a sensor,        (2) Method of applying a stereo camera system consisting of a plural number of CCD cameras as sensors, and        (3) Method of using a range finder as a sensor.        
The silhouette of the curve-faced object as mentioned above is an apparent silhouette whose shape consecutively varies according to the position/posture of the object concerned, and it is difficult to estimate and measure its position accurately. Therefore, the objects traced by the above-mentioned prior arts (1) or (2) were limited to those having fixed-edge structures that are invariable according to observing directions, such as polyhedrons, cylinders, etc., but arbitrary-curve-faced objects with smooth faces have never been traced by those prior arts. In the prior art (3) above, objects of free forms including arbitrary-curve-faced objects can be traced by utilizing the three-dimensional information on the surface, but a special type of sensor such as a high-speed laser range finder is needed for that purpose.